P0123

Diagnostic Chart:

Wiring Diagram:

Circuit Description

The PCM supplies a 5 V reference signal and a ground to the sensor. The Throttle position (TP) sensor sends a voltage signal back to the PCM relative to the throttle plate opening. Voltage will vary from approximately 0.45 V at closed throttle, to over 4.5 V at wide open throttle.

Conditions for Setting the DTC

^ Engine is running.

^ TP sensor voltage is greater than 3.9 V for 5 seconds.

^ MAP is less than 60 kPa. Engine speed is less than 1500 RPM.

^ DTCs P0107 or P0108 not set.

OR

^ TP sensor voltage is greater than 4.8 V.

^ DTCs P0107 or P0108 not set.

Action Taken When the DTC Sets

^ The Malfunction Indicator Lamp (MIL) will illuminate.

^ The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records buffers.

^ A history DTC is stored.

^ Coolant fan turns ON.

^ The TP angle will default to 0% when the vehicle speed is less than 2 mph (3 km/h) and 10% when the vehicle speed is greater than 2 mph (3 km/h) (The scan tool will display the defaulted value).

Conditions for Clearing the MIL/DTC

^ The MIL will turn OFF after three consecutive ignition cycles in which the diagnostic runs without a fault.

^ A history DTC will clear after 40 consecutive warm up cycles without a fault.

^ DTC(s) can be cleared by using the scan tool.

Diagnostic Aids

If a DTC P0123 cannot be duplicated, the information included in the Freeze Frame data can be useful. Use the scan tool DTC information data to determine the status of the DTC. If the DTC occurs intermittently, using the DTC P0121 Diagnostic table may help isolate the problem.

^ With the ignition ON and the throttle at closed position, the voltage should read between 0.20 V and 0.90 V and increase steadily to over 4.5 V at wide open throttle.

^ DTCs P0123 and P0113 stored at the same time could be the result of an open sensor ground circuit.

Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table.

1. The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data taken when the malfunction occurred. The information is then stored in the scan tool for later reference.

2. With the throttle closed, the TP sensor voltage should read less than 0.90V. If the TP sensor voltage does not read less than 0.90V check for a binding or sticking throttle cable.

4. With the TP sensor disconnected, the TP sensor voltage should less than 0.2V if the PCM and wiring are OK.

5. Probing the ground circuit with a test light checks the circuit for high resistance which will cause a DTC P0123 to set.

7. A shorted 5 volt reference circuit will also set additional DTCs.

11. The replacement PCM must be programmed and the crankshaft position system variation procedure must be preformed. Refer to the latest Tech line procedure for PCM reprogramming and also refer to Powertrain Control Module for the Crankshaft Position System Variation Procedure.